Fiber optic gyroscopes are known to be very sensitive to rotation. Therefore, fiber optic gyroscopes are used as an alternative to (or in addition to) mechanical gyroscopes to collect rotational rate data.
Referring to FIG. 1, a typical fiber optic gyroscope 10 includes a beam splitter 12 (e.g., a 2×2 coupler) that splits the light from a light source 14 (e.g., a superluminescent diode) into two beams, and directs the two light beams into the two opposed ends 16, 18 of an optical fiber coil 20. Therefore, two light waves propagate in opposite directions through the optical fiber coil 20. An isolator 15 may be interposed between the light source 14 and the beam splitter 12, and a depolarizer 13 may be interposed between the beam splitter 12 and the fiber coil 20. An integrated optical circuit 17 may modulate the light at a certain frequency such that the processing of the detected signal by the detector 22 is easier and more sensitive.
Pursuant to the Sagnac effect, rotation of the optical fiber coil 20 establishes a phase shift between the two light waves. Therefore, the fiber optic gyroscope 10 includes a detector 22 to measure the phase shift. A data processor 24 may correlate the measured phase shift to a rate of rotation (e.g., angular velocity) of the optical fiber coil 20.
In addition to rotation, various environmental factors may affect the measured phase shift and, as such, may compromise the accuracy of the rotational rate measurements taken by fiber optic gyroscope. These environmental factors include, for example, the temperature gradient across the optical fiber coil, local stress within the optical fiber coil, vibration and magnetic fields.
Thus, various attempts have been made to minimize the effects of environmental factors on fiber optic gyroscopes. Nonetheless, despite advances already made, those skilled in the art continue with research and development efforts in the field of fiber optics and rotation sensing.